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    1   package org.apache.lucene.queryParser.core.nodes;
    2   
    3   /**
    4    * Licensed to the Apache Software Foundation (ASF) under one or more
    5    * contributor license agreements.  See the NOTICE file distributed with
    6    * this work for additional information regarding copyright ownership.
    7    * The ASF licenses this file to You under the Apache License, Version 2.0
    8    * (the "License"); you may not use this file except in compliance with
    9    * the License.  You may obtain a copy of the License at
   10    *
   11    *     http://www.apache.org/licenses/LICENSE-2.0
   12    *
   13    * Unless required by applicable law or agreed to in writing, software
   14    * distributed under the License is distributed on an "AS IS" BASIS,
   15    * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   16    * See the License for the specific language governing permissions and
   17    * limitations under the License.
   18    */
   19   
   20   import org.apache.lucene.messages.MessageImpl;
   21   import org.apache.lucene.queryParser.core.QueryNodeError;
   22   import org.apache.lucene.queryParser.core.messages.QueryParserMessages;
   23   import org.apache.lucene.queryParser.core.parser.EscapeQuerySyntax;
   24   
   25   /**
   26    * A {@link SlopQueryNode} represents phrase query with a slop.
   27    * 
   28    * From Lucene FAQ: Is there a way to use a proximity operator (like near or
   29    * within) with Lucene? There is a variable called slop that allows you to
   30    * perform NEAR/WITHIN-like queries. By default, slop is set to 0 so that only
   31    * exact phrases will match. When using TextParser you can use this syntax to
   32    * specify the slop: "doug cutting"~2 will find documents that contain
   33    * "doug cutting" as well as ones that contain "cutting doug".
   34    */
   35   public class SlopQueryNode extends QueryNodeImpl implements FieldableNode {
   36   
   37     private static final long serialVersionUID = 0L;
   38   
   39     private int value = 0;
   40   
   41     /**
   42      * @param query
   43      *          - QueryNode Tree with the phrase
   44      * @param value
   45      *          - slop value
   46      */
   47     public SlopQueryNode(QueryNode query, int value) {
   48       if (query == null) {
   49         throw new QueryNodeError(new MessageImpl(
   50             QueryParserMessages.NODE_ACTION_NOT_SUPPORTED, "query", "null"));
   51       }
   52   
   53       this.value = value;
   54       setLeaf(false);
   55       allocate();
   56       add(query);
   57     }
   58   
   59     public QueryNode getChild() {
   60       return getChildren().get(0);
   61     }
   62   
   63     public int getValue() {
   64       return this.value;
   65     }
   66   
   67     private CharSequence getValueString() {
   68       Float f = Float.valueOf(this.value);
   69       if (f == f.longValue())
   70         return "" + f.longValue();
   71       else
   72         return "" + f;
   73   
   74     }
   75   
   76     @Override
   77     public String toString() {
   78       return "<slop value='" + getValueString() + "'>" + "\n"
   79           + getChild().toString() + "\n</slop>";
   80     }
   81   
   82     public CharSequence toQueryString(EscapeQuerySyntax escapeSyntaxParser) {
   83       if (getChild() == null)
   84         return "";
   85       return getChild().toQueryString(escapeSyntaxParser) + "~"
   86           + getValueString();
   87     }
   88   
   89     @Override
   90     public QueryNode cloneTree() throws CloneNotSupportedException {
   91       SlopQueryNode clone = (SlopQueryNode) super.cloneTree();
   92   
   93       clone.value = this.value;
   94   
   95       return clone;
   96     }
   97   
   98     public CharSequence getField() {
   99       QueryNode child = getChild();
  100   
  101       if (child instanceof FieldableNode) {
  102         return ((FieldableNode) child).getField();
  103       }
  104   
  105       return null;
  106   
  107     }
  108   
  109     public void setField(CharSequence fieldName) {
  110       QueryNode child = getChild();
  111   
  112       if (child instanceof FieldableNode) {
  113         ((FieldableNode) child).setField(fieldName);
  114       }
  115   
  116     }
  117   
  118   }

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